1. Field of the Invention
The present invention relates to fatty polypropoxylate esters of aliphatic and aromatic monocarboxylic fatty acids. These compounds have unique pigment dispersion and emolliency properties. The fatty polypropoxylate esters of the present invention are particularly useful in the formulation of sunscreen lotions, sunscreen sprays, self-tanning compositions, make-ups and other pigmented products, cold creams, lotions, skin moisturizers, antiperspirants, after shaves, pre-electric shaves, topical pharmaceutical products, lipsticks and cleansing creams. The present invention further relates to topical preparations incorporating the fatty polypropoxylate esters of the present invention.
2. Prior Art
There has been an increased awareness among the public of the potential for skin damage from ultraviolet radiation, with frequent news reports of greater risk from sun-induced photo aging, melanoma, and other skin disorders. The contribution of UVA radiation as well as the widely recognized contribution of UVB radiation to skin damage has engendered the development of a broad range of sunscreen products from the cosmetic industry. Sophisticated sunscreen formulations have been developed which incorporate combinations of UVA and UVB absorbers in vehicles which provide wash-off resistance and enhanced esthetics. Because of the regulatory limitations on the levels at which organic sunscreens may be used in formulations and the desirability for high absorbency formulations (high SPF) with broad spectrum protection, the use of physical sunscreens in conjunction with organic sunscreens in formulations has increased greatly.
Physical sunscreens consist of very finely divided (micronized) inorganic metallic oxides, typically Titanium Dioxide or Zinc Oxide. These micronized physical sunscreens appear transparent on the skin by virtue of their small particle size. Similar to other finely divided particulate products used in cosmetic formulations such as pigments for foundations and makeups, micronized Zinc Oxide and micronized Titanium Dioxide are dispersed within the formulation by mixing, using either low-shear or high-shear methods. In order to make stable, cosmetically acceptable products, uniform dispersions must be produced, with all particles wetted out and which remain in suspension over a period of time without settling, gelling or agglomerating. Producing such stable suspensions has proved to be a challenge, although some successes have been achieved.
For example, U.S. Pat. No. 5,116,604 to Fogel describes the use of neopentanoate esters, in particular isoarachidyl neopentanoate, as cosmetic emollients for sunscreen products. U.S. Pat. No. 5,716,602 to Uick describes sunscreens formulated to include a water resistance agent and an insect repellent. One form has in an aqueous emulsion DEET, a sunscreen agent, an anionic surfactant, an alkylated PVP, and octyldodecyl neopentanoate. Both of these inventions use of Elefac I-205, i.e., Octyldodecyl Neopentanoate.
U.S. Pat. No. 5,476,643 to Fogel describes the use of two specific neopentyl glycol diesters, as wetting, dispersing, spreading and deterging agents for micronized TiO2, ZnO and other pigments. These esters, neopentyl glycol di-2-ethyl hexanoate and neopentyl glycol di-isostearate, are used in varying combinations and may also be used with an emulsifying agent for a water dispersible pigmented make-up cleaner composition.
Emollients such as Finsolv TN (C12-C15 Alkyl Benzoate) and TRIVENT NP-13 (Tridecyl Neopentanoate) have also been employed with some success as dispersants for physical sunscreens, as have various glycols and propoxylates, such as PPG-3 Myristyl Ether. See for example, U.S. Pat. No. 5,928,631 to Lucas which describes a skin composition for controlling environmental malodors on the body. The composition comprises from about 0.1% to about 5%, by weight of a solubilized, water-soluble, uncomplexed cyclodextrin; from about 0.1% to about 36%, by weight of an oil phase selected from the group consisting of emollients, moisturizers, and skin protectants; one or more surfactants, and an aqueous carrier.
Still, there remains a need for superior dispersants with desirable esthetic properties for use in pigmented cosmetic compositions, particularly sunscreen formulations that contain physical sunscreens.
Additionally, since formulators often find it useful to fully disperse pigments, e.g., micronized metallic oxides, in a portion of the oil phase by high shear techniques such as milling, there is a need for forming oil phase dispersions which have a high solids content of pigments, particularly micronized metallic oxides, that are fluid.
It is a broad object of the present invention to provide a class of agents with superior dispersant properties suitable for use in the formulation of topical personal care products.
It is another object of this invention to provide compounds which are superior dispersants and have desirable esthetic properties for use in pigmented cosmetic compositions.
It is a further object of this invention to provide compounds which are superior dispersants, and have desirable esthetic properties for use in sunscreen formulations containing physical sunscreens.
It is yet another object of this invention to provide a dispersant that is useful for formulating by high shear techniques, such as milling, oil phase dispersions that have a high solids content of pigments and micronized metallic oxides.
It is a more specific object of this invention to provide dispersing agents having improved dispersant properties that are polypropoxylated fatty alcohol chains covalently bonded by ester linkages to aliphatic and aromatic monocarboxylic acids.
The aforedescribed objects and others are achieved through the present invention. Broadly, the invention is directed to certain aliphatic and aromatic monocarboxylic acid esters of polypropoxylated fatty alcohols. These compounds demonstrate unusual and unexpectedly superior properties as pigment dispersants, especially for micronized Zinc Oxide, e.g., Z-Cote HP-1 from BASF, micronized Titanium Dioxide, and uncoated pigments such as those used in foundations and makeup products. Additionally, these propoxylated alcohol esters can be used to produce uniform milled dispersions of pigments and micronized metallic oxide sunscreens that have exceptionally high solids content, exhibit unusual fluidity and when applied to the skin demonstrate a dry, elegant emolliency.
Generally, the fatty polypropoxylate esters of this invention are esters of an aliphatic or an aromatic monoacid formed by reacting an acid with a stoichiometric excess of a polypropoxylated fatty alcohol.
Broadly, the compounds of this invention have the following structural formula: 
wherein R1 is derived from a polypropoxylated fatty alcohol and has the structural formula: 
wherein R5 is a saturated or unsaturated, substituted or unsubstituted aliphatic or aromatic moiety containing from 4 to 24 carbon atoms, and x is an integer from 3 to 30; and
wherein R is derived from an aliphatic or aromatic monocarboxylic acid and has the structural formula: 
xe2x80x83wherein R2, R3 and R4 are independently selected from the group consisting of methyl, ethyl, propyl or isopropyl; or 
xe2x80x83wherein R6 is H or OH or NH2 or methyl or ethyl.
The present invention provides fatty polypropoxylate esters possessing exceptional pigment dispersant and esthetic emollient properties long sought by formulators for use in personal care and topical pharmaceutical preparations.
In accordance with another aspect of the present invention, there are provided compositions for topical application that include such the fatty polypropoxylate esters.
The emollient dispersants of the present invention are fatty polypropoxylate esters of aliphatic and aromatic monocarboxylic acids.
The aliphatic monocarboxylic acids suitable for preparing the compounds of the present invention contain from 2 to 24 carbon atoms. The aromatic monocarboxylic acids suitable for preparing the compounds of the present invention contain from 7 to 9 carbon atoms. Preferred aliphatic monocarboxylic acids contain from 4 to 18 carbon atoms. Examples of suitable aliphatic monocarboxylic acids include 2-Ethyl Hexanoic acid, Caproic acid, Neopentanoic acid, Isostearic acid, Neoheptanoic acid and Oleic acid. Examples of suitable aromatic moncarboxylic acids include Benzoic acid and p-Aminobenzoic acid.
The fatty polypropoxylate esters of the present invention are formed by reacting the above described aliphatic and aromatic monocarboxylic acids with polypropoxylated fatty alcohols. The polypropoxylated fatty alcohols preferably have between 3 and 30 moles of propoxylation, and most preferably between 3 and 10 moles of propoxylation. The fatty alcohols utilized to prepare these polypropoxylated fatty alcohols may be saturated or unsaturated, substituted or unsubstituted, aliphatic or aromatic, and may be straight chained or branched chained, having between 6 and 24 carbon atoms. Saturated aliphatic fatty alcohols, either straight chain or branched chain, with 12 to 14 carbon atoms are most preferred.
The fatty polypropoxylated esters of the present invention are particularly useful as agents that confer superior pigment dispersion and unusual, dry, elegant emollient properties to topical formulations, especially to those containing physical sunscreens and other pigments. The fatty polypropoxylated esters of the present invention are also singularly useful in the preparation of fluid, high solids content dispersion grinds of micronized physical sunscreens such as Zinc Oxide and Titanium Dioxide for use in sunscreen formulations. The esters are useful in the formulation of sunscreen lotions, sunscreen sprays, self-tanning compositions, make-ups and other pigmented products, cold creams, skin moisturizers, antiperspirants, after shaves, pre-electric shaves, topical pharmaceutical products, lipsticks and cleansing creams. The dry, elegant emolliency imparted by the fatty polypropoxylated esters of the present invention is manifested primarily when the esters are utilized as a full or partial replacement for the mineral oil and petrolatum emollient agents of the prior art. A distinct improvement in the esthetics and emollient properties of mineral oil and petrolatum-based products is discernible when as little as 25% of the mineral oil or petrolatum has been replaced by the fatty polypropoxylated esters of the present invention. Therefore, topical preparations in accordance with the present invention can include a second emollient agent of mineral oil, petrolatum and the like along with the fatty polypropoxylated esters of the present invention in a ratio of up to about 3:1 of the second emollient agent to the emollient agent of the present invention. These topical formulations include the essential compounds of the present invention, one or more active ingredients and water. As mentioned above, a second emollient agent of mineral oil, petrolatum and the like may be included as desired. Suitable active ingredients for use in topical preparations include organic sunscreens, physical sunscreens, self-tanning agents, pigments, opacifying agents, moisturizers, film-formers, thickening agents, emulsifiers, antiseptic agents, conditioning agents and deodorant actives.
The topical preparations of the present invention, in addition to including the primary components of the fatty polypropoxylated esters of the present invention, one or more active ingredients, water and the optional second emollient agent, may also include fragrances, humectants, protein derivatives, coloring agents, preservatives and the like.
Typical topical formulations in accordance with the present invention include the essential fatty polypropoxylated esters of the present invention either alone or in combination with the second emollient agent, in a range of from about 0.2% to about 40.0% by weight of the composition, preferably from about 2.0% to about 20.0% of the composition. As noted above, the second emollient agent, when present, may be blended with the fatty polypropoxylate ester emollients of the present invention in a ratio of about 3:1 of the former to the latter.
The topical preparations of the present invention are formulated using techniques that are well known to practitioners in the cosmetic formulating art. Typically, the ingredients are combined with mixing and the application of heat as necessary until a homogeneous product is obtained. The water soluble ingredients and water-insoluble ingredients are mixed together separately and combined with suitable emulsifying agents.
The topical compositions of the present invention are topically applied directly to the skin. The compositions can be delivered by placing the composition into a dispensing means and applying an effective amount via spraying or rubbing the composition onto the desired skin surface, either the entire body or selected portions thereof. Preferably the dispensing means is a wipe or a spray dispenser. Distribution of the composition of the present invention can also be achieved by using a pre-formed applicator such as a roller, pad, sponge, tissue, cotton ball, hand, etc. Alternatively, the user may combine the composition of the present invention with a wipe substance of his or her own choosing. To do this, the user simply chooses a wipe substance such as a commercial paper towel, tissue, sponge, cotton, pad, washcloth, or the like; and pours, from a bottle or other suitable container, a solution of the composition of the present invention over the chosen wipe substance and applies the composition to the desired area of the body. In this manner, the user may use as much or as little of the composition of the present invention as he/she desires, depending upon their intended use.
The following examples set forth below are intended to illustrate certain aspects of the present invention, and are not to be considered limiting as to the scope and nature of the present invention.